It's D&D. It's a realm, like Forgotten Realms, or Eberron or the like.
of course he might not know what any of them are either
incase he doesnt:
Dungeons & Dragons is essentially generic, that is the rules themselves dont really* contain a specific setting.. you buy the rules, then you either buy a separate setting or make up your own.. Greyhawk was the first ever setting ~ back before D&D was even published, Greyhawk was the setting the designers were playing in.
* its an implied setting with elves and orcs and dwarves and such, but thats it, the only real setting specific things in the basic game are the gods list and a few wizard spells named after their creators ~ all of which are from Greyhawk
"Living" games are sort of authorised tournament roleplaying games run by the RPGA (Roleplaying Games Association), of which Living Greyhawk is one (there were about a dozen Living games on the go at one point i believe, most of them were D&D campaign settings, but there were a few other games aswell i believe)
